Aqueous liquid and gel detergent compositions containing enzymes, including amylases, are well known in the art. The major problem encountered with such compositions is that of ensuring a sufficient storage stability of the enzymes in the compositions. It is particularly difficult to stabilize amylases in the presence of proteases, which can readily degrade amylases in aqueous liquid or gel detergent compositions.
High-alkaline amylases such as alpha amylases are described in British Specification No. 1,296,839. The use of an enzyme stabilizing system comprising a mixture of boric acid or an alkali metal borate with calcium ion, and preferably with a polyol, is disclosed in U.S. Pat. No. 4,537,706, Severson. Certain α-amylases that provide improved cleaning and stain removal are disclosed in WO97/32961, Baeck et al., and in WO96/23873 and U.S. Pat. No. 6,093,562.
The present invention utilizes low levels of boric acid and polyhydroxy compound in combination with a relatively high level of calcium ion to provide surprisingly good stability of selected α-amylase enzymes.